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rs.next() is returning false in while statement

So, I'm trying to extract msgID and msgStatus values from database for each reference Id(variable msgRefList) stored in the list object and I'm trying to store these extracted values in String objects for further processing. But rs.next() method is returning false and hence it is not going into the while loop where the assignment statements are. I checked in database with the query that i'm using in the code and it shows one record in the result, but still rs.next() is returning false. Screenshot attached with the database results.
Below is the actual code that i'm using
List<String> msgRefList = listofRefrnceValues:
try {
Connection connect = connectToDB(ENV);
for(String reference: msgRefList){
String query="select ID, MSG_STS from TABLE where INSTR_ID = ?";
PreparedStatement stmt = connect.prepareStatement(query);
stmt.setString(1,reference);
ResultSet rs = stmt.executeQuery();
if(rs!=null){
while(rs.next()) {
P_MID = rs.getString("P_MID");
P_MSG_STS = rs.getString("P_MSG_STS");
}
}
}
}catch (Exception e) {
e.printStackTrace();
}

You have some typos in your SQL-Query-String in java. Instead of TABLE you probably meant MINF (your real table) also all of your properties don't have the prefix P_ and ID is probably MID. So change:
String query="select ID, MSG_STS from TABLE where INSTR_ID = ?";
To:
String query="select P_MID, P_MSG_STS from MINF where P_INSTR_ID = ?";
And you'll be fine.

Proper use of Stored Procedure using Select

I created a Stored Procedure where I can select the column that I address in my Stored Procedure via Callable Statement. I tried to use SELECT SECTION NAME FROM allsections_list WHERE SECTION_NAME = ? Similar to syntax of Prepared Statement but I think its not compatible using this syntax. I'm just new learning this mysql.
Stored Procedure
CREATE STORED PROCEDURE getSECTION_NAME(OUT SECTION_NAME VARCHAR)
SELECT SECTION_NAME FROM allsections_list
Code
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
String searchSection = Section_SearchSection_Textfield.getText();
String searchSection_Name = Section_SectionName_TextField.getText();
if (searchSection.isEmpty())
{
JOptionPane.showMessageDialog(null, "Please fill up this fields");
}
else
try (Connection myConn = DBUtil.connect();
CallableStatement myCs = myConn.prepareCall("{call getSECTION_NAME(?)}"))
{
myCs.setString(1, searchSection_Name);
try (ResultSet myRs = myCs.executeQuery())
{
int resultsCounter = 0;
while (myRs.next())
{
String getSection_Name = myRs.getString(1);
Section_SectionName_TextField.setText(getSection_Name);
resultsCounter++;
}
}
}
catch (SQLException e)
{
DBUtil.processException(e);
}
When I search a records. If the records exist it the value will print out to the textfields. But it doesn't print out. And it throws me a error getSECTION_NAME does not exist. What if I want select multiple values? Because I'm having a project where I'm making a Enrollment System. I choose this Stored Procedure specially than Batch Statement based on what I read. Any help will appreciate. Thanks!

I don't use MySql, but here's a similar example in Oracle (I think this Works in MySql as well).
CREATE PROCEDURE get_section_name(OUT secName VARCHAR(100))
BEGIN
SELECT SECTION_NAME INTO secName FROM allsections_list WHERE some_condition = 100; //your procedure does not use any input arguments if you want to return just one record then you'll probably need to specify a where clause
END
/ //when executing a stored procedure in a DB client you will need to specify a terminator character (in this case slash /)
Note that there's no return statement because we're using OUT parameters.
The getOutValueForStoredProcedure method calls the stored procedure and retrieves the out value.
public String getOutValueForStoredProcedure(String procedureName, int sqlType) throws EasyORMException{
String out=null;
CallableStatement stmt=null;
try{
//out parameters must me marked with question marks just as input parameters
sqlQuery = "{call " + procedureName +"(?)}";
stmt=conn.prepareCall(sqlQuery);//I assume that a Connection has been created
stmt.registerOutParameter(1, sqlType);
stmt.execute();
out = stmt.getString(1);//you get the out variable through the Statement, not the ResultSet
}catch(Exception e){
//log exception
}finally{
//close stmt
}
return out;
}
To call this stored procedure, you can use
String out = getOutValueForStoredProcedure("get_section_name", java.sql.Types.VARCHAR);
For creating stored procedures in MySql , check this link http://code.tutsplus.com/articles/an-introduction-to-stored-procedures-in-mysql-5--net-17843
For a more elaborate example, check this http://www.mkyong.com/jdbc/jdbc-callablestatement-stored-procedure-out-parameter-example/

How to return result sets from Stored Procedure?

I created a Stored Procedure where I can fetch all my data that I inserted in my following textfields. How can I fetch all of this data by calling my Callable Statement? I think this is the easiest way than Batch Statement based on what I read. I only drag and drop this following components just a practice purposes.
Stored Procedure
CREATE PROCEDURE show_data(OUT FULLNAME VARCHAR(50), OUT ADDRESS VARCHAR(50))
PARAMETER STYLE JAVA
LANGUAGE JAVA
READS SQL DATA
DYNAMIC RESULT SETS 1
EXTERNAL NAME 'Frame.searchButton'
I used OUT parameter to retrieve values using getXXX() methods. I'm just little bit confuse since this is my first time to use Stored Procedure in derby.
GUI
After the user search the following record in Database. If the value exist it will print to the designated textfields.
SOURCE CODE
String searchRecord = searchTf.getText();
String searchQuery = "SELECT * FROM SAMPLEONLY";
ResultSet data[] = null;//Why should I use this array?
try (Connection myConn = DriverManager.getConnection(url, user, pass);
PreparedStatement myPs = myConn.prepareStatement(searchQuery);)
{
String addFullname = fullnameTf.getText();//first field
String addAddress = addressTf.getText();//second field
data[0] = myPs.executeQuery();
CallableStatement cs = myConn.prepareCall("{ call showData(?, ?)}");
cs.setString(1, addFullname);
cs.setString(2, addAddress);
boolean hasResults = cs.execute();
if (hasResults) {
ResultSet rs = cs.getResultSet();
while (rs.next()) {
String getFullname = rs.getString(1);//get the value
String getAddress = rs.getString(2);
fullnameTf.setText(getFullname);//set the text here
addressTf.setText(getAddress);
}//end of while
rs.close();//close the resultset
}//end of if
}//end of try
catch (SQLException e)
{
e.printStackTrace();
}
}//end of else
}
After I insert in Search textfields it throws me a error NullPointerExeption. I follow Derby Reference Manual so I can have a guide writing a proper Stored Procedure. This code is mine most of the part. Guide me if I missed something wrong. Feel free to comment thanks.

fill jcombobox from database depending on text from textfield

I want to fill the jComboBox with values from database. and these values depend on the text written in the textfield.
eg: if I write a in the texfield, the combobox will have all values starting with a. The values are from a databse
Here's my code:
private void FillCombo(){
String url = "jdbc:mysql://localhost:3306/pharmacy";
String driver = "com.mysql.jdbc.Driver";
String user = "root";
String pass = "test";
String sql = "select medicinename from medicine where medicinename like '%"+jTextField5.getText()+"%'";
try{
Class.forName(driver).newInstance();
System.out.println("1");
Connection con = (Connection)DriverManager.getConnection(url,user,pass);
System.out.println("Connected");
Statement st=(Statement) con.createStatement();
PreparedStatement pst = con.prepareStatement(sql);
ResultSet rs = pst.executeQuery();
while(rs.next()){
String name = rs.getString("medicinename");
jComboBox1.addItem(name);
}
} catch(Exception e){
JOptionPane.showMessageDialog(null, e);
}}

I want not just one caracter eg: if i write a, as, asp it fill aspirine myproblem is that the combobox is already filled. want it empty when i start.
Simply use JComboBox#removeAllItems() to removes all items from the item list on each stroke of any key in the JTextField.
Points to Remember
Don't load driver each time you enter a new character. Move it outside the FillCombo() method.
Use PreparedStatement instead of using single quoted query string that may cause issue. Find a sample on Using Prepared Statements
Don't forget to close the resources such as connection, result set and statement.
Use finally block to handle it or Read more about Java7 -The try-with-resources Statement

Getting an Integer From MySQL Select Statement

I would like to get an integer saved in my MySql DB into an Integer in Java. I have a Table, that includes PlayerName and Level. I would like to get The Level (Integer) From a Specific Player. And then Add Integer "Value" to it. Then put it back in the DB. My Code up to now is:
public void addinputPData(String loc, int value, Player player, String playername){
//add input Player Data
try{
logm("Putting Kill Death Int Data into " +player.getName() + "'s Profile!");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/WebCom", "root", "MyPW");
int ovalue = -1;
Statement stmt = (Statement) con.createStatement();
ResultSet rs = stmt.executeQuery("SELECT "+loc+" FROM PlayerData WHERE PlayerName='"+playername+"'");
if(rs.next()){
ovalue= rs.getInt(loc);
}
if(ovalue == -1){
logm("Error Occured");
}
int nvalue = value + ovalue;
String insert = "UPDATE PlayerData SET "+ loc + "='" + nvalue + "' WHERE PlayerName='" + playername + "'";
stmt.executeUpdate(insert);
con.close();
}catch(Exception e){
logm("Could Not Send Data To MYSQL DATABASE SERVER s: "+ e.getMessage());
}
}
I don't know why this won't work, Is there anything obvious that i am missing? Thank you in advance.

So first what you must understand is that when you won't use parametrized statements, there is big danger of SQL Injection. So your code is very dirty written.
So anyway, use PreparedStatement with parametrized SQL statements for much more better performace. Now rewrite your code like this:
final String SELECT_QUERY = "SELECT level FROM PlayerData WHERE PlayerName = ?";
final String UPDATE_QUERY = "UPDATE PlayerData SET level = ? WHERE PlayerName = ?";
public boolean dataMethod(String playerName) {
Connection con = null;
PreparedStatement ps = null;
PreparedStatement ps1 = null;
ResultSet rs = null;
int dataLevel = 0;
try {
// getConnection etc...
ps = con.prepareStatement(SELECT_QUERY);
ps.setString(1, playerName) // first param is order of ? param, starts with 1(not 0)
rs = ps.executeQuery();
while (rs.next()) {
dataLevel = rs.getInt();
}
if (dataLevel > 0) {
ps1 = con.prepareStatement(UPDATE_QUERY);
ps1.setInt(1, dataLevel);
ps1.setString(2, playerName);
ps1.executeUpdate();
}
return true;
}
catch (SQLExcetion ex) {
Logger.getLogger(YourClass.class.getName()).log(Level.SEVERE, null, ex);
return false;
}
finally {
if (con != null) {
con.close();
}
}
}
Step by step, first init your statement, sets parameters if you have then when you use select, you will retrieve data in ResultSet that is table of data generated with query. imlicitly cursor in ResultSet is position before first row so you have to use next() method to go on current row and with the help of getter method you add data from ResultSet to your variable. Then you check if it's correct, if do, init second statement and execute it. And that's all.
But you should consider when you use more that 1 operation, sets autoCommit on false and all operations will do in one Transaction, because implicitly in JDBC is one operation = one transaction. And second, you should consider to use SQL stored procedures for add any data, update data or delete. It's more safer yet and less code. So let database working when it able to do it and also it's faster of course.
At the last, really you should think about this approach and makes your code more safer, faster and cleaner. Not have look on simplicity but on efficiency, compability and security.
More about SQL Injection
And when you decided right to use stored procedure, you can use it like this:
CREATE OR REPLACE PROCEDURE SOME_NAME(VARCHAR v_name PlayerData.name%type)
AS
BEGIN
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
// body
COMMIT;
EXCEPTION
WHEN OTHERS THEN
ROLLBACK;
END;
So now you have to create String for call procedure.
final String CALL_SOMENAME = "{call SOME_NAME(?)}";
Then intead of PreparedStatement you have to use CallableStatement that is interface used to execute SQL stored procedures.
cs.prepareCall(CALL_SOMENAME); // Creates a cs object for calling db stored procedures
cs.setString(1, playerName);
cs.execute();
I don't know why many people searching the easiest way to do something and don't look at performance and readability of code.
Regards

In the UPDATE statement, you're inserting the value for the "loc" column as a string (there are single quotes around the value). If the database column is an integer, then this could be causing a problem.
Tip: JDBC provides a class called PreparedStatement. This class allow you to build SQL queries safely. It makes sure that all user input is properly escaped in order to avoid security vulnerabilities.
PreparedStatement ps = con.prepareStatement("UPDATE PlayerData SET " + loc + " = ? WHERE PlayerName = ?");
ps.setInt(1, nvalue);
ps.setString(2, playername);
ps.execute();